Seedance 2.5 API Guide: Modelflare Setup, Pricing, and Model Comparison
A fact-checked Seedance 2.5 guide covering its 30-second workflow, differences from 2.0, comparison with current video models, Modelflare pricing, and asynchronous API calls.
ByteDance Seedance 2.5 is a joint audio-video generation model built around a practical change: a single generation can tell a story for up to 30 seconds. ByteDance also highlights more precise reference-video understanding, broader editing control, and production-oriented tools such as white-model control and green-screen editing.
That does not make every Seedance 2.5 integration identical. A model can have capabilities that a particular API does not expose. This guide separates ByteDance's official model claims from the fields available through Modelflare, then compares Seedance 2.5 with Seedance 2.0, Veo 3.1, Kling 3.0 Pro, Runway Gen-4.5, and Sora 2 using current documented contracts rather than promotional demo rankings.
All volatile availability and Modelflare pricing facts below were checked on August 15, 2026.
Seedance 2.5 at a glance
| Property | What is currently documented |
|---|---|
| Model family | ByteDance Seedance |
| Core architecture | Joint audio-video generation |
| Maximum native clip | Up to 30 seconds in one generation |
| Continuation | The official page says a result can be extended twice |
| Reference control | More precise interpretation of reference-video intent, framing, and cinematic language |
| Editing | Broader audio and visual editing requests, with more reliable instruction response |
| Production controls | White-model control, green-screen editing, camera movement, and performance blocking |
| Modelflare model ID | seedance-2.5 |
| Modelflare public surface | Asynchronous Video API for text-to-video and single-image-to-video |
The official page does not publish a parameter count, training-compute figure, or a neutral cross-provider benchmark. It also does not substantiate several numbers repeated by third-party launch articles. This guide therefore does not treat claims such as a particular reference-asset count as official Seedance 2.5 API limits.
What changed from Seedance 2.0
Seedance 2.0 already combined text, image, video, and audio input in one audio-video model. ByteDance documents up to 9 images, 3 video clips, and 3 audio clips for its full reference workflow, along with 15-second multi-shot output, stereo audio, video editing, and extension.
| Decision point | Seedance 2.0 | Seedance 2.5 | Practical effect |
|---|---|---|---|
| Native duration | Up to 15 seconds | Up to 30 seconds | 2.5 can hold a longer beat or scene without a stitch-first workflow |
| Reference workflow | Explicit mixed-reference limits are documented | Reference-video interpretation is emphasized, but no numeric limit appears on the official page | 2.0 has the clearer published input contract; 2.5 targets finer interpretation |
| Editing | Prompt-directed editing and continuation | Broader, more reliable audio-visual editing | 2.5 is the better candidate when revision control matters more than first-pass cost |
| Production control | Camera planning and multimodal direction | Adds emphasis on white models, green screens, camera movement, and blocking | 2.5 is aimed more directly at controlled production pipelines |
| Current Modelflare price | Lower | 50% higher at every listed resolution | 2.0 remains the economical baseline when 15 seconds and simpler control are enough |
The upgrade is therefore not simply “twice the duration.” Its intended value is fewer continuity breaks, stronger interpretation of reference footage, and more controllable revision. Those advantages need to be tested on your own shots; a longer clip is more expensive to discard when identity, hands, dialogue, or motion fails late in the generation.
Horizontal comparison with other video models
The table compares current API contracts, not image quality scores. Provider demos use different prompts, safety policies, resolutions, durations, sampling, and post-processing, so they cannot support a fair universal ranking.
| Model | Documented single-generation duration | Audio and control surface | Best fit |
|---|---|---|---|
| Seedance 2.5 | Up to 30 seconds | Joint audio-video; stronger reference interpretation and editing; professional white-model and green-screen controls | Longer directed scenes and production workflows that value continuity |
| Seedance 2.0 | Up to 15 seconds | Native stereo audio; up to 9 images, 3 videos, and 3 audio references in the full native workflow | Lower-cost Seedance work and clearly specified multimodal reference jobs |
| Veo 3.1 | 4, 6, or 8 seconds | Native audio always on; first/last frames, up to 3 reference images, and Veo-only extension; 720p, 1080p, or 4K under documented constraints | Short high-resolution shots and Google-native workflows |
| Kling 3.0 Pro | 3–15 seconds on the referenced API host | Optional native audio, multi-prompt shots, custom elements, and motion control | Multi-shot planning, element consistency, and motion-driven clips |
| Runway Gen-4.5 | 2–10 seconds | Text-to-video and image-to-video; the core generation endpoint does not expose native-audio generation | Teams already using Runway's creation and editing environment |
| Sora 2 | 4, 8, or 12 seconds | Synced audio and optional image reference; current OpenAI API catalog marks the model Legacy | Existing Sora integrations that have already evaluated the legacy lifecycle |
Seedance 2.5 has the clearest native-duration advantage in this set. Veo 3.1 has a tightly documented resolution and extension contract, Kling 3.0 Pro exposes direct multi-shot and element controls, and Runway offers a broader production environment around shorter generations. Sora 2 remains useful context, but its current Legacy label makes it a weak default for a new long-lived integration.
No specification table can tell you which model will preserve your actor, product, camera path, or dialogue best. Run the same licensed inputs and shot brief through the candidates, then compare usable-shot rate, revision count, wall time, and total cost—not only the first output.
Which Seedance version should you choose?
- Choose seedance-2.5 when a continuous 16–30-second scene, reference interpretation, or later editing control is worth the price premium.
- Choose seedance-2.0 when the shot fits within 15 seconds, budget matters, or you want ByteDance's explicitly documented mixed-reference limits.
- Split a story into shorter shots when one late artifact would force an expensive long clip to be regenerated.
- Keep both model IDs behind the same application abstraction. Their Modelflare submission, polling, and download flow is the same, so controlled A/B routing does not require a second job system.
Seedance pricing on Modelflare
At the production check, both exact model IDs were available only in the public seedance-stable group through the openai-video protocol. The live effective prices below are in US dollars per generated second.
| Resolution tier | Seedance 2.0 | Seedance 2.5 | 2.5 premium |
|---|---|---|---|
| 480p | $0.12/s | $0.18/s | 50% |
| 720p | $0.24/s | $0.36/s | 50% |
| 1080p | $0.60/s | $0.90/s | 50% |
| 4K | $1.20/s | $1.80/s | 50% |
A 10-second 720p request is therefore $2.40 on 2.0 or $3.60 on 2.5 before any future pricing change. A 30-second 720p 2.5 request is $10.80. The current catalog has a price row for all four tiers, but a price row is not a promise that every duration, resolution, input mode, or account combination will be accepted upstream.
Use the live Seedance 2.5 pricing page and Seedance 2.0 pricing page before a batch. Modelflare's initial integration verification completed a 4-second 480p Seedance 2.5 image-to-video task and a matching Seedance 2.0 text-to-video task; both produced an approximately 4.064-second MP4 with video and two-channel audio. That proves those exact paths at the verification time, not a permanent service-level guarantee for every combination.
Call Seedance 2.5 through Modelflare
Seedance uses an asynchronous Video API. Submit a job, save the public task ID, poll until a terminal state, and then download the content. Do not send this request to /v1/chat/completions.
Submit a text-to-video task
export MODELFLARE_API_KEY="<YOUR_MODELFLARE_API_KEY>"
curl https://modelflare.dev/v1/videos \
-H "Authorization: Bearer $MODELFLARE_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "seedance-2.5",
"prompt": "A white cat runs through a neon-lit street in the rain, cinematic low-angle tracking shot, natural foot contact, synchronized city ambience",
"duration": 4,
"resolution": "720p"
}'
The response includes id and task_id for the same public task. Persist one of them with your application job record.
Submit an image-to-video task
Add one publicly reachable HTTPS image URL. This switches the current Modelflare surface to image-to-video.
curl https://modelflare.dev/v1/videos \
-H "Authorization: Bearer $MODELFLARE_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "seedance-2.5",
"prompt": "The subject turns slowly toward the camera while the camera moves forward; preserve identity, clothing, composition, and natural lighting",
"image": "https://example.com/licensed-reference.png",
"duration": 4,
"resolution": "720p"
}'
The current public contract accepts one image field. Do not infer support here for ByteDance's full native multi-image, video-reference, audio-reference, white-model, green-screen, or editing controls until those fields are explicitly documented by Modelflare.
Poll and download the result
Poll every few seconds with bounded backoff. Continue through queued, pending, processing, or in_progress; stop at completed or failed.
export TASK_ID="<TASK_ID_FROM_SUBMISSION>"
curl "https://modelflare.dev/v1/videos/$TASK_ID" \
-H "Authorization: Bearer $MODELFLARE_API_KEY"
After completion, download through the authenticated content endpoint instead of depending on an upstream storage URL:
curl -L "https://modelflare.dev/v1/videos/$TASK_ID/content" \
-H "Authorization: Bearer $MODELFLARE_API_KEY" \
-o seedance-2.5.mp4
The complete request and status contract is also maintained in the Seedance API setup document.
Production checklist and limitations
- Use an API key eligible for seedance-stable and pin the exact model ID.
- Start with a 4-second 480p or 720p request before spending on a long, high-resolution clip.
- Validate that every source image is licensed, publicly reachable over HTTPS, and free of expiring query parameters during generation.
- Store your own job ID, Modelflare task ID, model, prompt version, requested duration, resolution, timestamps, final state, and recorded charge.
- Make submission retries idempotent in your application; repeating a timed-out POST can create and bill a second task.
- Poll with backoff and a deadline. Treat 429 as temporary capacity pressure, and do not retry invalid 400 parameters unchanged.
- Download and archive successful output according to your retention policy instead of assuming provider storage is permanent.
- Compare models on usable-shot cost. Include failed generations, discarded takes, editing time, and regeneration—not just dollars per generated second.
AI video can still produce identity drift, malformed hands or text, inconsistent object permanence, physically implausible motion, and audio artifacts. Human review remains necessary before advertising, publishing, or using generated footage in a customer workflow.
Bottom line
Seedance 2.5 is the stronger Seedance candidate when a 30-second native scene and more deliberate reference or editing control reduce stitching and revision work. Seedance 2.0 remains compelling when 15 seconds is enough: on Modelflare it currently costs one-third less than 2.5, uses the same job protocol, and has a more explicit published mixed-reference contract at the model level.
Against other video models, 2.5's differentiator is long native storytelling plus production-oriented control—not a proven win on every visual-quality dimension. Keep the integration asynchronous, test short and cheap first, and choose by usable outputs per dollar on your own licensed workload.
Official sources and update log
Primary and API sources:
- ByteDance Seed: Seedance 2.5
- ByteDance Seed: Seedance 2.0 official launch
- Google AI: Generate videos with Veo 3.1
- OpenAI API: Sora 2 model
- Runway API: available models and Gen-4.5 contract
- fal API: Kling 3.0 Pro contract
Update log:
- August 15, 2026: Initial publication. Official model pages, competitor API contracts, Modelflare model availability, effective prices, public fields, and the earlier real-task verification record were checked.